The present invention relates to a method for producing a polyglycerol nanogel.
Various methods for producing polyglycerol nanoparticles or polyglycerol nanogels are known from prior art (A. L. Sisson, I. Papp, K. Landfester, R. Haag, Macromolecules 2009, 42, 556-559;                A. L. Sisson, D. Steinhilber, T. Rossow, P. Welker, K. Licha, R. Haag, Ang. Chem. Int. Ed.2009, 48, 7540-7545; D. Steinhilber, A. L. Sisson, D. Mangoldt, P. Welker, K. Licha, R. Haag, Adv. Funct. Mater. 2010, 20, 4133-4138; H. Zhou, D. Steinhilber, H. Schlaad, A. L. Sisson, R. Haag, React. Funct, Polym. 2011, 71, 356-361).        
Also, EP 2 138 527 A1, for example, specifies a method for producing polyglycerol nanoparticles. According to this prior art method, mini or micro emulsions are formed in order to produce nanoparticles. In the method, it is always worked using a surface-active substance. Moreover, at various stages of the method an ultrasound treatment takes place. Also, the reaction temperatures are sometimes quite high. Under conditions that harsh, it is not possible to encapsulate substances that are chemically or physically sensitive to temperature, interfacial effects, ultrasound and extreme pH values, such as proteins, for instance, in the thus-formed polyglycerol nanogels while maintaining the activity.
From US 2009/0011420 A1 polymer nanogels are known which are formed by means of radical cross-linking Such a radical cross-linking is incompatible with an embedding of labile biomolecules in such a nanogel; the radicals persistently damage the labile biomolecules and, moreover, can inactivate them (Pattison, David I., Aldwin Suryo Rahmanto, and Michael J. Davies. “Photo-oxidation of proteins.” Photochemical & Photobiological Sciences 11.1 (2012): 38-53.). Hence, the nanogels specified in that US patent application are not suited for the embedding of labile biomolecules, but instead for the electrophoretic separation of DNA molecules after the formation of the nanogels has taken place.
From DE 10 2008 030 992 A1 polyglycerol compounds are known which consist of a purely hydrophobic nucleus, which practically excludes the encapsulation of hydrophilic substances. Furthermore, basically only a low load efficiency with hydrophilic substances is to be expected due to the encapsulation in the aqueous phase. Thus, in said patent application no suitable method with which labile biomolecules can effectively be embedded in a polyglycerol compound is specified.